Defrosting appliance



April 5, 1949. C, J, ROAQH 2,466,479

DEFROSTING APPLIANCE Filed Dec. 7, 1946 21h64, f2 j] MTTORN EY=S- Patented Apr. 5, 1949 U NJITEID `S TAT'ES PATENT OF FICE :DEFROSTING APPLIANCE Charles lRoach, Hamilton, Ohio ApplicationDecember 7, 1946, Serial No. 714,731

9 Claims.

This invention relates tof a defrosting.- appliance and more particularly to a kdevice Whichmay .be used for defrosting the evaporator orireezing compartment of a refrigerator.

Substantially all refrigerators with whichI am acquainted are provided with acooling unit or evaporator with `which `is generally associated a freezing compartment. Such freezing compartment may be used for-the `storage of frozen food packages and it may `also be used forfthe production of ice cubes.

-Generallythe walls .of .the freezing compartment carry :tubing in whichthe refrigerant circulates during its evaporation stage, and .the cooling is1produced by the evaporation of the refrigerant. Since the evaporator walls are Ausually thevcoolest portion ofthe refrigerator, if .there is any moisture within the atmosphere lof .the refrigerator, that moisture Willcondenseouton the evaporator walls; and since walls of the evaporator are at a'temperature below freezing-the condensed moisture freezes. After -a period of time, depending upon the amountof humidity in the atmosphere, .a thick coating of ice will have been formed. Such a coating :of ice greatly impairs vthe efficiency of the refrigerator and must be periodically removed.

The ice layer is usual-ly removed by ahousewife by an operation known as defrosting, in which the refrigerator motoris-turnedoi, and the box is opened tothe atmosphere of the kitchen until the-ice layer has melted off or has been rremoved .by prying with .a knife orlother instrument. VSuch practices, of course,-tend to injure the evaporator and besides foods .-may spoil, because of `the length of Ytime usually required for defrosting,

With the above dilculties in mind, it vis an object of my invention to .providea device by means of which a refrigeratorfreezing compartment may be defrosted very rapidly and easily. It is another object of my invention .to provide a device `as .outlined above, which will `be relatively inexpensive, simple in use and which Will have .a long life. Furtherobjects of myinvention include the provision of ,a .device as outlined, which will be safe and will remove the possibility of injury t the user.

These and other objects of my invention which will be pointed out hereinafter, .or which will be apparent to one skilled v.inthe art upon reading these specifications/I accomplish by that .certain construction and arrangementof parts of which I shall now describe an exemplary embodiment.

Reference is made to'the drawings forming a part hereof and in which:

`Fig.'l`is a plan view with parts in cross-section `of'a device according tomy invention.

Fig. 2 'is a sideV elevation thereof, 'with parts in. cross-sectionpn theline"2-2 .of.Fig, .11,

Fig. 3isa cross-sectional view taken on the lined-3 ofJFigureZ.

Fig. 4 is an. .end elevation as Seen from theright of Fig. `2.

Fig. I5 is a partial vertical cross sectional View through arefrigerator and the freezing compartment-thereof showing vthe device in use.

,Brieflyin the practiceof my invention .I providea vented housing within which I provide .a heating element. The housing is preferably'of the general proportionsl of the ice cube tray .for the .particular refrigerator with kwhich it lis to be used, andis preferably of nonconductive material suchas one of the plastics, or is'suitably insulated. Means are provided for connecting said .heating element toa source of y electric current. .Preferablya time switch vris incorporated into the device, so--that the electric circuit to the heating element will automatically bez'interrupted after a relatively short interval of time, such as five minutes.

4Thehousin-g protects the-heating element from the drippings attendant upon a defrosting .operation, ybut the housingis vented to the lsides and bottom Ito permit circulation of heated air through .the housing. The bottom cover isremovable sothat access may be thad t0 the heating velement for replacement or repair, and the cover element, when` in closedposition, prevents accidentalinjury whichwould result from touching the heatingelement.

Referring more particularly to the drawings, the device is indicated `generally -at 'I0 in the gures and comprises a housing having a top Wall -I l, which is imperforate, side walls lf2 fand i3, a rearsend Wall l5. The side walls Ir2'and'lf3 are provided with .openingsI-ll whichv extend substantially vthe length of the device and which preferably flare-upwardly as fbest seenin -Fig. y3. The ytop wall H f may ',be provided with some sort of handle arrangement such as the ring I7 pivotally lmounted ina -boss I8. AA recess I'la may be yprovided in thermember ll'to accommodate thering Il when it is not in use.

Within the housing Iprovidea bafiieextending the entire length. and width ofthe housingvwhich baffle ispreferably metallic and: is highly reflective yon-its lower side. The -baffle is indicatedat lfand is vpreferably shaped to :lie fairly closely adjacent the heating element to be described hereinafterand thence to are upwardly atthe sides to the upper edges of the vents M. The baiile I9 may be provided with a numberof ears ISafWhich are'seated in recesseslgb in the `side walls l2 and l3-of the housing. .Preferablyalso the baffle is backed with alayer ofheat insulating material such as asbestos indicatedE at 2li.

.A `bottom element isindicated at 2| and is provided -with feet 22 at itsfourtcorners. -A series of 4.transverse .slots *.23 are provided for the-circulation of air to the heating element. The heating element itself may be of horseshoe shape and may comprise a ribbon of resistance wire 24 wound on an insulating core 25. The heating element rests in grooves 26 formed in the bottom member 2| and the ends of the resistance wire are connected as by means of wires 35 to the time switch indicated generally at 36 which will be described hereinafter.

The bottom structure 2| is fastened to the housing I by means of screws 3`| at the four corners.

Mounted upon the 'front panel is a time switch having a control indicated generally at 21. Since the particular switch forms no part of my invention, I shall not describe it in detail, except that I prefer a switch which is settable to various time periods up to about five minutes. I have found in practice that a period of four or ve minutes is adequate, as will be described hereinafter, and I prefer to have the heating element turned off at the end of the period so that if the housewife is called to the telephone or the like, it makes no difference if she forgets to disconnect the heating element.

Electrical current is supplied to the device by plugging the member 28 into a suitable floor or wall plug. It will be understood that when the electrical current is supplied to the heating element, air currents will be set up with air being drawn in through the slots 23 past the heating element, and out through the lateral slots I4. This circulation is, of course, enhanced by the refleeting quality of the baffle I9.

In Fig. 6 I have shown a more or less conventional refrigerator 30 having a freezing compartment indicated generally at 3|. The particular compartment shown has four shelves 32 for supporting ice cube trays which are indicated at 33. The number of shelves in the freezing compartment forms no limitation on my invention, since I have used it successfully on various commercial refrigerators with various numbers of shelves. Conventionally, there is provided a large dish 34 immediately under the freezing unit 3| to collect any moisture drippings off the freezing unit.

In the drawing, I have shown my device in use in the lowermost shelf.

In practice, my device is inserted preferably in the lowermost shelf first and centrally of the freezing compartment, and the time switch is set for, say ve minutes. As soon as the period is completed, the device is removed and placed in the next higher shelf and the cycle is repeated. Thus, in a freezing compartment, as shown, it would take at the most 20 minutes to defrost the freezing compartment. I have found the first operation will melt the ice from the bottom and the lower portions of the sides, and with each successive operation the defrosting is carried farther up the sides until the defrosting is complete. The melting ice is caught, of course, in the receptacle 34 and may easily be disposed of. It will be understood also that the refrigerator motor is turned off while the defrosting operation is in progress.

It will be seen that heat is supplied to the particular locations where it is needed and only long enough to loosen the ice layer from its contact with the walls of the freezing compartment. In many of the smaller commercial refrigerators only two shelves are provided and, of course, there the defrosting operation may be carried out still more rapidly. I prefer to use a fiat electric cord 28a so that the door of the refrigerator may be practically shut whereby entrance of Warm air into the cabinet is largely prevented.

Thus, it will be seen that by the use of my device a refrigerator may be defrosted very rapidly and economically, because it will not be necessary to let the entire freezing unit and the entire interior of the refrigerator become warm. Therefore, when the defrosting operation is complete, the refrigerator motor may be turned on again, and there will have been very little loss in refrigeration.

It will be understood that numerous modifications may be made in my invention, and I therefore do not intend to limit myself except as pointed out in the claims which follow.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A device of the character described, comprising an insulated housing having the general proportions of an ice cube tray, `said housing being provided with a `plurality of `air vents, a heating element mounted in said housing, said heating element being so positioned as to provide a relatively large air space Within said housing, means for connecting said heating element to a source of electric current, Iand means for automatically disconnecting said lhea-ting element from said source of currentl after a predetermined time interval.

2. A device of the character described, compri-sing Aa hol-low insulated shell member having the general proportions of an ice cube tray,

vents in the side walls of said member, a closure member for said shell member, vents in said 4clousre member, feet at the corners of said closure member, means for releasably holding said closure member in position, a heating element mounted within said Ishell member, and means for connecting said heating element with a source of electric current.

3. A device according to claim 2 in which means are provided for interrupting said connection after a predetermined interval of time.

4. A device of the character described comprising a hollow non-conductive shell member having the general proportions of an ice cube tray, Vents in the side walls of said member, a bottom closure for said shell member, said bottom closure being provided with feet and hav- 'ing vents to permit circulation of air, an electric heating element mounted on said bottom closure member and a reflective baille mounted within said shell member above said heating element to cause air entering through the vents of said bottom closure to leave through the Vents of said side walls and means for `connecting said heating element to a source of electric current.

5. A device according to claim 4 in which said vents in the side walls flare outwardly and in which said bale is inclined laterally to correspond with the flare of said vents.

6. A device according to claim 4 in which said vents in the side walls flare outwardly and in which said baille is inclined laterally to correspond with the flare of said vents, and in which means are provided for interrupting said connection after a predetermined interval of time.

7. A device of the character described, comprising a hollow insulated shell member having the general proportions of anice cube tray, vents in the side walls of said member, a. bottom closure member for said shell member, vents in said closure member, meansv to hold said device ing a hollow insulated shell member having the general proportions of an ice cube tray, vents in the side walls of said shell member, vents in the bottom of said shell member, means to hold said device in spaced relation to a supporting surface so that air may reach the vents in the bottom of said shell member, a heating element mounted Within said shell member, a reilective baille mounted within said shell member yabove said heating element to icause air entering through the vents in :the bottom of said shell member to leave through the vents of said side Walls, and means for connecting said element to a source of eleotric current.

9. A defrosting device of the character described, comprising `an insulated, inverted panshaped housing having a removable bottom and having the general proportions of an ice cube tray, said housing being' provided with a plurality lof air vents, said air vents being positioned 6. only in `the side walls `and bottom of said housing, a heating element mounted in said housing so as to provide a relatively large air space within said housing, means for connecting said heating element to a source of electric current, and means to hold said device in spaced relation to a supporting surface so `that air may reach :the vents inthe bottom of said housing.

CHARLES J. ROACI-I.

REFERENCES CITED The following references are of record in the le oi this patent:

UNITED STATES PATENTS Number Name Date 1,533,175 Fahrenwald Apr. 14, 1925 1,882,901 Reichart Oct. 18, 1932 1,974,146 Barnes Sept. 18, 1934 2,112,263 Bohannon et al. Mar. 29, 1938 2,153,050 Pfaiile Apr, 4, 1939 FOREIGN PATENTS Number Country Date 444,200 Great Britain Mar. 16, 1936 

